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The multimammate mouse, Mastomys natalensis, is the most common rodent pest species in sub‐Saharan Africa. Currently, rodenticides are the preferred method used to reduce the population of rodent pests, but this method poses direct and indirect risks to humans and other non‐target species. Fertility control is a promising alternative that has been argued to be a more sustainable and humane method for controlling rodent pests. In this study, we compared the effectiveness of fertility control bait EP‐1 (quinestrol (E) and levonorgestrel (P), 10 ppm) and an anticoagulant rodenticide bait (bromadiolone, 50 ppm) on the population dynamics of M. natalensis in maize fields in Zambia during 2 cropping seasons. M. natalensis was the most abundant species in maize fields (77% of total captures). Fertility control reduced the number of juveniles and suppressed population growth of M. natalensis at the end of the 2019–2020 cropping season. The population density initially decreased after rodenticide treatment, but the population rapidly recovered through immigration. None of the treatments influenced maize damage by rodents at germination (F2,67 = 1.626, P = 0.204). Applying the treatments during the maize seeding time was effective at suppressing population growth at the end of the cropping season than application the month before maize seeding. This research indicates that a single‐dose delivery of EP‐1 and rodenticide have comparable effects on the population dynamics of M. natalensis. These findings are important in developing fertility control protocols for rodent pest populations to reduce maize crop damage and improve yields. [ABSTRACT FROM AUTHOR]

Background. Oviposition site selection is an important factor in determining the success of insect populations. Orius spp. are widely used in the biological control of a wide range of soft-bodied insect pests such as thrips, aphids, and mites. Orius strigicollis (Heteroptera: Anthocoridae) is the dominant Oriusspecies in southern China; however, what factor drives its selection of an oviposition site after mating currently remains unknown. Methods. Here, kidney bean pods (KBPs) were chosen as the oviposition substrate, and choice and nonchoice experiments were conducted to determine the preferences concerning oviposition sites on the KBPs of O. strigicollis. The mechanism of oviposition behavior was revealed through observation and measurement of oviposition action, the egg hatching rate, and the oviposition time. Results. We found that O. strigicollis preferred the seams of the pods for oviposition, especially the seams at the tips of the KBPs. Choice and nonchoice experiments showed that females did not lay eggs when the KBP tail parts were unavailable. The rates of egg hatching on different KBP parts were not significantly different, but the time required for females to lay eggs on the tip seam was significantly lower. Decreased oviposition time is achieved on the tip seam because the insect can exploit support points found there and gain leverage for insertion of the ovipositor. Discussion. The preferences for oviposition sites of O. strigicollis are significantly influenced by the topography of the KBP surface. Revealing such behavior and mechanisms will provide an important scientific basis for the mass rearing of predatory bugs. [ABSTRACT FROM AUTHOR]

BACKGROUND: In plant–insect interactions, phytotoxins such as gossypol, exert a defensive role on behalf of the plant by interfering with the essential metabolic, biochemical and physiological pathways of herbivorous insects. The beet armyworm, Spodoptera exigua (Hübner), is a key pest for many important crops including a range of vegetables, ornamentals, and cotton. In this study, we investigated how resistance to deltamethrin relates to enzyme activity in gossypol‐pretreated larvae of S. exigua. RESULTS: Following selection with deltamethrin insecticides on gossypol‐pretreated larvae for 10 generations, the Gos‐SEL population developed a 113.29‐fold resistance. Under the same conditions, the Delta‐SEL selected population showed a 69.76‐fold increase in resistance along with corresponding levels of xenobiotic defense enzyme activity. Similarly, the fecundity of the Delta‐SEL population together with male and female longevity were found to be significantly lower when compared with the Gos‐SEL population and the laboratory susceptible‐strain group (SS‐Strain). In addition, the activities of cytochrome P450s in S. exigua were significantly enhanced when the insects were fed on a deltamethrin and gossypol‐pretreated diet compared with being fed on deltamethrin alone. CONCLUSION: The reproductive capacity of S. exigua is significantly reduced in Delta‐SEL and Gos‐SEL populations compared with the control group (SS‐Strain). Elevation of the major detoxification enzyme cytochrome P450 monooxygenase and esterase might have an important role in inducing tolerance to deltamethrin in gossypol‐fed S. exigua populations. This study enhances our understanding of detoxification enzyme pathways for S. exigua gene expression and their role in responses to insecticides and plant secondary metabolites. © 2018 Society of Chemical Industry Graphical figure shows the induced effect of gossypol on resistance to pyrethroid insecticide, enzymes activity and fitness gain parameters of spodoptera exigua. [ABSTRACT FROM AUTHOR]

The aphid sex pheromone component (4aS,7S,7aR)-nepetalactone is considered to be a potential tool for enhancing biological control of aphids. Studies have confirmed its potential to attract parasitoids, increase parasitism rates in the field and also alter the spatial distribution of parasitoids. An important aspect that has been overlooked is the impact that the introduction of nepetalactone may have on aphid populations already present in field or glasshouse environments. The most prevalent pest aphid populations in glasshouse and field environments are the asexual morphs, which are capable of exponential growth if populations are not controlled. The short-term implications of the sex pheromone on asexual aphids were observed through their behavioural response. Using Y-tube olfactometry, it is shown that virginoparae of the peach-potato aphid, Myzus persicae, are repelled by high concentrations of nepetalactone. Long-term effects of the pheromone which may span the aphid's life, or even generations, were assessed via mean relative growth rate (MRGR) and the intrinsic rate of natural increase (rm). Electroantennography also demonstrated that asexual female aphids are able to detect aphid sex pheromone components. To our knowledge, this is the first time it has been reported that M. persicae virginoparae are able to detect aphid sex pheromone components or that their behavioural response and/or performance has been studied. The implications of these results and their significance in understanding semiochemical communication are discussed. [ABSTRACT FROM AUTHOR]

How herbivorous insects adapt to host plants is a key question in ecological and evolutionary biology. The fall armyworm, (FAW) Spodoptera frugiperda (J.E. Smith), although polyphagous and a major pest on various crops, has been reported to have a rice and corn (maize) feeding strain in its native range in the Americas. The species is highly invasive and has recently established in China. We compared behavioral changes in larvae and adults of a corn population (Corn) when selected on rice (Rice) and the molecular basis of these adaptational changes in midgut and antennae based on a comparative transcriptome analysis. Larvae of S. frugiperda reared on rice plants continuously for 20 generations exhibited strong feeding preference for with higher larval performance and pupal weight on rice than on maize plants. Similarly, females from the rice selected population laid significantly more eggs on rice as compared to females from maize population. The most highly expressed DEGs were shown in the midgut of Rice vs. Corn. A total of 6430 DEGs were identified between the populations mostly in genes related to digestion and detoxification. These results suggest that potential adaptations for feeding on rice crops, may contribute to the current rapid spread of fall armyworm on rice crops in China and potentially elsewhere. Consistently, highly expressed DEGs were also shown in antennae; a total of 5125 differentially expressed genes (DEGs) s were identified related to the expansions of major chemosensory genes family in Rice compared to the Corn feeding population. These results not only provide valuable insight into the molecular mechanisms in host plants adaptation of S. frugiperda but may provide new gene targets for the management of this pest. [ABSTRACT FROM AUTHOR]

Simple Summary: Insect pest resistance to synthetic insecticides is a major problem that limits efficient management and thus decreases productivity for farmers and increases the use of harmful materials that pollute the environment and endanger humans and beneficial organisms. A major approach for resistance management is understanding how insect pest field populations develop resistance at molecular levels. To provide a comprehensive insight into the resistance mechanisms of Spodoptera frugiperda larvae to lambda-cyhalothrin 5%, we investigated the molecular basis of resistance mechanism in field collected population of fall armyworm (Spodoptera frugiperda) to lambda-cyhalothrin 5% insecticide, a pyrethroid insecticide by using de novo transcriptomics analysis. We found that resistance to lambda-cyhalothrin 5% can be metabolic by increasing the levels of detoxifying enzymes such as P450, GST and UGT and related genes to insecticide resistance in the field population. The obtained transcriptome information provides large gene resources available for further studying the resistance development of Spodoptera frugiperda to pesticides. The DGE data provide comprehensive insights into the gene expression profiles of fall armyworm (Spodoptera frugiperda) to lambda-cyhalothrin 5% and will facilitate the study of the role of each gene in lambda-cyhalothrin resistance development. The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a polyphagous, invasive insect pest which causes significant losses in important crops wherever it has spread. The use of pesticides in agriculture is a key tool in the management of many important crop pests, including S. frugiperda, but continued use of insecticides has selected for various types of resistance, including enzyme systems that provide enhanced mechanisms of detoxification. In the present study, we analyzed the de novo transcriptome of S. frugiperda larvae exposed to Noposion Yihaogong® 5% emulsifiable concentrate (EC) insecticide focusing on detoxification genes and related pathways. Results showed that a total of 1819 differentially expressed genes (DEGs) were identified in larvae after being treated with Noposion Yihaogong® 5% EC insecticide, of which 863 were up- and 956 down-regulated. Majority of these differentially expressed genes were identified in numerous Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including metabolism of xenobiotics and drug metabolism. Furthermore, many of S. frugiperda genes involved in detoxification pathways influenced by lambda-cyhalothrin stress support their predicted role by further co-expression network analysis. Our RT-qPCR results were consistent with the DEG's data of transcriptome analysis. The comprehensive transcriptome sequence resource attained through this study enriches the genomic platform of S. frugiperda, and the identified DEGs may enable greater molecular underpinnings behind the insecticide-resistance mechanism caused by lambda-cyhalothrin. [ABSTRACT FROM AUTHOR]

The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) is a highly polyphagous pest which causes considerable economic losses to cotton and many vegetable crops. Tannins are among the most important secondary metabolites in cotton plants. We show that tannic acid enhances the toxic effect of chlorantraniliprole on S. exigua when presented in combination. Bioassays using third-instar S. exigua larvae on an artificial diet showed that consumption of tannic acid with chlorantraniliprole at the concentration of (2 mg/g and LC 50 0.018 mg/L) had higher toxicity when compared to either chlorantraniliprole or tannic acid alone (LC 50 0.027 mg/L). The diet containing tannic acid with chlorantraniliprole significantly prolonged larval and pupal developmental time and extended mean generation time and total pre-oviposition period compared to either chemical alone. Moreover, fecundity, survival rate, reproductive value, intrinsic rate of increase, finite rate of increase and net reproduction rate declined significantly when exposed to the combined treatment. No difference was observed between tannic acid and the control. Meanwhile, tannic acid with chlorantraniliprole had markedly antifeedant effects; causing significant decline in the relative growth rate (RGR), the relative consumption rate (RCR), the efficiency of conversion of ingested food (ECI), the efficiency of conversion of digested food and an increase in the approximate digestibility (AD) compared to either chemical alone. Tannic acid with chlorantraniliprole also decreased the insect's carbohydrate, lipid and protein contents significantly. The results showed that the interaction between tannic acid and chlorantraniliprole on the growth inhibition of larvae was additive and tannic acid increased the toxicity of chlorantraniliprole to insects. The results of this study provide information useful in integrated pest management programs for S. exigua and show that tannic acid combined with chlorantraniliprole may be a route to reducing the use of synthetic pesticides., (Copyright © 2019. Published by Elsevier Inc.)